Sinclair Laurel E, Fortin Richard, Buckle John L, Coyle Maurice J, Van Brabant Reid A, Harvey Bradley J A, Seywerd Henry C J, McCurdy Martin W
*Geological Survey of Canada, Natural Resources Canada, Ottawa, Ontario, Canada.
Health Phys. 2016 May;110(5):458-70. doi: 10.1097/HP.0000000000000491.
A series of experiments was conducted in 2012 at the Defence Research and Development Canada's Suffield Research Centre in Alberta, Canada, during which three radiological dispersal devices were detonated. The detonations released radioactive (140)La into the air, which was then carried by winds and detectable over distances of up to 2 km. The Nuclear Emergency Response group of Natural Resources Canada conducted airborne radiometric surveys shortly following the explosions to map the pattern of radioactivity deposited on the ground. The survey instrument suite was based on large volume NaI(Tl) scintillation gamma radiation detectors, which were situated in a basket mounted exterior to the helicopter and oriented end-to-end to maximize the sensitivity. A standard geophysical data treatment was used to subtract backgrounds and to correct the data to produce counts due to (140)La at the nominal altitude. Sensitivity conversion factors obtained from Monte Carlo simulations were then applied to express the measurements in terms of surface activity concentration in kBq m(-2). Integrated over the survey area, the results indicate that only 20 to 25% of the bomb's original inventory of radioactive material is deposited within a 1.5-km radius of ground zero. These results can be accommodated with a simple model for the RDD behavior and atmospheric dispersion.
2012年，在加拿大艾伯塔省的加拿大国防研究与发展部萨菲尔德研究中心进行了一系列实验，期间引爆了三个放射性散布装置。爆炸将放射性（140）镧释放到空气中，随后被风吹送，在长达2公里的距离内都可检测到。加拿大自然资源部的核应急响应小组在爆炸后不久进行了空中辐射测量调查，以绘制地面上放射性沉积物的分布图。测量仪器套件基于大体积碘化钠（铊）闪烁伽马辐射探测器，这些探测器安装在直升机外部的吊篮中，并首尾相连以最大化灵敏度。使用标准的地球物理数据处理方法来减去背景并校正数据，以得出标称高度下（140）镧产生的计数。然后应用从蒙特卡罗模拟获得的灵敏度转换因子，以贝可勒尔每平方米（kBq m(-2)）为单位的表面活度浓度来表示测量结果。在整个调查区域进行积分，结果表明，炸弹原始放射性物质存量中只有20%至25%沉积在距爆心投影点1.5公里半径范围内。这些结果可以用一个关于放射性散布装置行为和大气扩散的简单模型来解释。
